Remove the grill for easier access. Remove the intercooler pipes. Remove the water pipe which is connected to the thermostat (you will lose some coolant here so don't do this after you have removed the oil filter)

Remove the oil filter and fill the hole with a clean rag. As far as I remember the thermostat is held on with 3 bolts (maybe they are torx type which will be annoying if you don't have the right tools) You will need to carefully remove a fuel line bracket and slide it to one side so you can slide the thermostat straight out. Don't forget to unclip the electric connector.

Getting the new thermostat in is slightly fiddly (make sure the old o-ring comes off and the new one stays in place) and now it is just a case of putting everything back.

Don't forget to put the cab heater on full, run the engine and top up the coolant, while you are at it, check for leaks where you have been working. It is better to notice now than later on